Optical films, including polymeric single layer optical films, polymeric multilayer optical films and polymeric optical films including disperse and continuous phases, are widely used for various purposes. Exemplary applications of polymeric optical films include display devices, such as liquid crystal displays (LCDs) placed in mobile telephones, personal data assistants, computers, televisions and other devices. Well known polymeric optical films include reflective polarizer films, such as Vikuiti™ Dual Brightness Enhancement Film (DBEF) and Vikuiti™ Diffuse Reflective Polarizer Film (DRPF), both available from 3M Company. Other well known polymeric optical films include reflectors, such as Vikuiti™ Enhanced Specular Reflector (ESR), also available from 3M Company.
Polymeric multilayer optical films used as polarizers or mirrors, usually include one or more first optical layers and one or more second optical layers. In addition to the first and second optical layers, some traditional multilayer films include one or more non-optical layers, such as one or more protective boundary layers located over or between packets of optical layers. The non-optical layers are usually integrated into the polymeric multilayer optical films so that at least a portion of the light to be transmitted, polarized, or reflected by the first and second optical layers also travels through these non-optical layers. Such non-optical layers can protect the optical layers from damage, aid in coextrusion processing and/or enhance post-processing mechanical properties of the optical films. Thus, in such traditional optical films, it is usually important that the non-optical layers do not substantially affect the reflective properties of the optical films over the wavelength region of interest.